This invention relates to connectors.
The invention is more particularly concerned with connectors for connection to the outside of tubes, such as epidural cannulae, and to assemblies including such connectors.
In known epidural cannula connectors, a cannula extends through a bore in a resilient slug. The slug is located between two halves of a housing that are screw threaded with one another. When the two halves of the housing are tightened, they compress the slug axially, thereby causing it to expand radially. The outer surface of the slug engages the inside of the housing and the bore through the slug is squeezed into sealing engagement with the cannula. One half of the housing has a female luer coupling, or other coupling, to which a cooperating connector can be mated. Examples of such connectors are described in U.S. Pat. No. 4,187,848, Brit J. Anaesth (1964) 36, pp 740, 741 and Brit J. Anaesth (1961), 33, pp 664, 665. Epidural connectors are available, such as from Portex Limited of Hythe, Kent, England under reference number 100/382.
One problem with these connectors is that, if they are over-tightened, there is a risk of crushing the cannula because of its small diameter, typically about 1 min. The problem is aggravated if the connector is to be used with cannulae of different diameters since the slug of the connector must be capable of sealing with the smallest of the cannulae, increasing the risk of crushing the larger cannulae.